ENISALA - the Fortress from Dobrogea...

The Enisala Fortress (often referred to as Heracleea Fortress) is a 12th to 14th century medieval fortress sitting high on a hill overlooking Lake Razim (Razelm) and a vast field of reed grass and water channels, in Tulcea County, Romania.

Byzantine citadel certified in 1270 had a great military importance while Razelm lake was a Black Sea Bay. The citadel was situated at the turning of two important comercial routes between the Orient and the North of Europe. It was controlled by the Genoveses for 150 years 
The fortress was first conquered by the Ottomans in 1388/1389, and retaken in 1416/1417 after a brief Wallachian rule (it belonged to Wallachia's Prince Mircea the Elder). It was conquered by Sultan Mehmet I in 1417 (who renamed it "o Yeni Sale"). Due to the new political situation and the development of sand spits that hampered trade, the fortress gradually decayed, and was finally abandoned around the end of the 15th century.
http://wikimapia.org/972075/Enisala-Fortress